The effect of contaminant source momentum on a worker's breathing zone concentration in a uniform freestream.
Am Ind Hyg Assoc J 1992 Dec; 53(12):757-766
A tracer gas method was used to analyze various factors which have an effect on the breathing zone concentrations found in a booth used for spray painting. The variables which were examined in this study included the contaminant momentum, the presence of a flat plate downstream from the workers, the distance from the source of the contaminant to the worker's body, and the motion of the worker during the painting operation. The concentrations of the contaminants in the breathing zone of the worker were significantly reduced when the spray gun which emitted contaminants had a higher momentum. Wind tunnel studies were conducted on the spray momentum by measuring the breathing zone concentrations of a mannequin using various flow rates through several jet diameters at varying free stream velocities. Breathing zone concentrations were slightly lower at lower free stream velocities at higher source flows than at the higher free stream velocity. This indicated that worker exposure is not always effectively measured by increasing the free stream velocity. Variables including breathing zone concentration, breathing zone concentration with the negligible source momentum, the source momentum, and the reverse flow momentum were all related through a mathematical expression. Numerical modeling supported this dependence of breathing zone concentration on contaminant momentum. By incorporating contaminant source momentum into a previous model which predicts breathing zone concentration at negligible source momentum it was possible to obtain a modified empirical model. The authors stress that application of this new model to actual working situations should be done with caution.
NIOSH-Publication; NIOSH-Grant; Control-technology; Spray-painting; Spraying-equipment; Construction-workers; Painters; Air-quality-monitoring; Air-sampling; Spraying-booths; Organic-vapors; Occupational-exposure
Environmental Sciences & Engr University of North Carolina Rosenau Hall 201H Chapel Hill, NC 27514
American Industrial Hygiene Association Journal
University of North Carolina Chapel Hill, Chapel Hill, North Carolina